This is really simple. You enter a month, day and year. Then you press the Day of the Week button and out pops a number from 0 to 6. Continue reading HP-65 STD01 Day of the Week Program →

The HP-65 calculator came with a “Standard Pac” of programs. That was a set of ready made solutions for some common problems. The idea was probably: if the calculator is programmable, it ought to come with some programs to show that off. It also effectively provided training material that created a whole lot of new programmers. It was a very good idea in many ways. Continue reading HP-65 Diagnostic Programs →